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CR prepress abstract   -  DOI: https://doi.org/10.3354/cr01736

Historical trends and future projections of annual rainfall from CMIP6 models in Ho Chi Minh City, Vietnam

Dang Nguyen Dong Phuong, Nguyen Duc Vu, Nguyen Kim Loi*

*Corresponding author:

ABSTRACT: Climate risks have posed a major threat to many local communities settling in low-lying coastal megacities across the globe, including Ho Chi Minh City, Vietnam. Hence, this study first aimed to contribute towards a comprehensive understanding of temporal trend patterns of annual rainfall and absolute extremes in Ho Chi Minh City over the last four decades (1980-2022) through multiple non-parametric statistical trend tests. Then, this study employed the quantile delta mapping (QDM) method to develop daily bias-corrected rainfall data based on the outputs in the latest Coupled Model Intercomparison Project phase 6 (CMIP6) under eight shared socio-economic pathway (SSP) greenhouse gas emission scenarios. Evaluation of model performance was implemented by repeatedly leaving successive five years out in turn for estimating testing errors. The outcomes imply the high applicability of well-calibrated transfer functions, even for high quantiles, to the production of future rainfall scenarios. The projected changes in annual rainfall and absolute extremes were obtained by estimating multi-model medians from CMIP6 models for future periods (i.e., 2021-2040, 2041-2060, 2061-2080, and 2081-2100), with reference to the base period (1995-2014). Generally, annual rainfall in Ho Chi Minh City is projected to increase substantially, and Thu Duc station is consistently responsible for the highest increases in annual rainfall, with the projected changes being approximately 30.9% (8.3% to 77.8%) under the high-end scenario (i.e., SSP5-8.5) by the end of the twenty-first century. There is the expectation that these findings would yield various solid grounds for mitigating climate-related risks in Ho Chi Minh City.